Abstract 3343Poster Board III-231 Background:lower alimentary tract mucositis (L-ATM), also known as neutropenic enterocolitis, is a complication of chemotherapy with high mortality rates. The incidence, risk factors and mortality of L-ATM remain unknown. Purpose:To determine the incidence, risk factors and mortality of L-ATM in a homogeneous population of patients with multiple myeloma. Patients and Methods:303 newly diagnosed myeloma patients (2004 - 2007) were enrolled in a protocol consisting of induction chemotherapy, tandem melphalan-based autologous stem-cell transplantation (ASCT) and consolidation. Lower -ATM was defined as grade II-IV enteritis/colitis occurring during neutropenia. All data were collected prospectively. The analysis of risk factors included body surface area (BSA), creatinine clearance (CrCl), serum albumin and other pretreatment variables. Multiple logistic regression model was used to compute adjusted odds ratio (OR) and 95% confidence intervals (CI). Results:47 patients (15.5%) developed L-ATM during 1528 chemotherapy cycles (including 536 ASCT). BSA < 2 m2 (OR 2.853; 95% CI 1.232, 6.607; p = 0.0144) and CrCl <60ml/min (OR 3.089; 95% CI 1.176, 8.114; p = 0.0221) increased the risk for L-ATM while higher serum albumin was protective (OR 0.695; 95% CI 0.517, 0.936; p = 0.0167). No L-ATM-related death was observed. Conclusions:Lower-ATM is not uncommon among myeloma patients undergoing multiple cycles of chemotherapy but does not contribute to mortality. The risk for L-ATM is determined by lower values of BSA, renal function and serum albumin. These findings have significant implications for the study and management of L-ATM in patients undergoing chemotherapy.Multivariate analysis: Risk factors for lower alimentary tract mucositis (L-ATM)Treatment stageVariablesControl group¤L-ATMBaselineN (%)N (%)OR (95% CI)p- valueALB (g/dL), unit = 0.539.97 ± 5.1237.79 ± 6.010.695 (0.517, 0.936)0.0167BSA (<2.0 m2)132 (61.97)39 (82.98)2.853 (1.232, 6.607)0.0144e-CrCl (<60 ml/min)31 (14.55)13 (27.66)1.534 (0.697, 3.375)0.2880Induction cycle 2ALB (g/dL), unit = 0.536.86 ± 4.0533.00 ± 3.220.347 (0.129, 0.934)0.0362BSA (<2.0 m2)186 (67.39)3 (50.00)0.567 (0.105, 3.073)0.5106e-CrCl (<60 ml/min)34 (12.32)1 (16.67)1.469 (0.153, 14.09)0.7390Transplant 1ALB (g/dL), unit = 0.538.60 ± 4.1135.53 ± 3.160.462 (0.248, 0.863)0.0154BSA (<2.0 m2)165 (64.71)15 (88.24)4.130 (0.874, 19.53)0.0735e-CrCl (<60 ml/min)21 (8.24)6 (35.29)3.688 (1.093, 12.44)0.0354Transplant 2ALB (g/dL), unit = 0.538.65 ± 4.2736.96 ± 4.450.748 (0.470, 1.190)0.2207BSA (<2.0 m2)139 (64.65)24 (92.31)5.906 (1.339, 26.05)0.0190e-CrCl (<60 ml/min)19 (8.84)5 (19.23)1.586 (0.505, 4.987)0.4299Transplants 1 +2(N=285)ALB (g/dL), unit = 0.538.79 ± 4.2336.41 ± 2.880.489 (0.304, 0.787)0.0032BSA (<2.0 m2)141 (62.39)33 (89.19)5.433 (1.779, 16.59)0.0030e-CrCl (<60 ml/min)16 (7.08)10 (27.03)3.089 (1.176, 8.114)0.0221Consolidation cycles 1+2ALB (g/dL), unit = 0.538.10 ± 3.7837.86 ± 4.060.899 (0.367, 2.201)0.8151BSA (<2.0 m2)130 (65.99)7 (100.0)..e-CrCl (<60 ml/min)15 (7.61)2 (28.57)3.162 (0.571, 17.51)0.1874Pre-treatment characteristics of 303 myeloma patients: Lower alimentary tract mucositis (LATM) vs. controlsAll patients N=303Control group ¤ N=213LATM N=47P-valueμCMV IgG positive, N (%)190 (62.7)139 (65.3)25 (53.2)0.1345Body Surface Area (BSA)†Median, m21.881.91.800.0253Range, m21.41-2.561.41 - 2.561.48 - 2.21< 2.01 m2201 (66.3)132 (62.0)39 (83.0)0.0063>= 2.01 m2102 (33.7)81 (38.0)8 (17.0)Melphalan dose for transplant cyclesTransplant 1N=285N=255N=17Median, mg/kg4.494.424.580.2329Range, mg/kg2.00-6.822.00 - 6.533.10 - 6.82Transplant 2N=251N=215N=26Median, mg/kg4.504.474.940.0250Range, mg/kg2.41-6.582.41 - 6.583.05 - 6.11Serum AlbuminMedian, g/dL443.90.0207Range, g/dL2.1-5.32.5 – 5.32.1 - 4.9Estimated creatinine clearanceMedian, ml/min93.895.287.70.1463Range, ml/min9.0 -245.79.0 - 245.79.9 - 172.4<60 ml/min49 (16.2)31 (14.6)13 (27.7)0.0505≥60 ml/min254 (83.8)182 (85.5)34 (72.3)Control group ¤: patients who did not develop enterocolitis (neutropenic or Clostridium difficile colitis (CDI)) during any cycle of therapy. 43 patients with CDI were excluded from analysis.†BSA cut off at 2 m2 is based on the highest tertile of the control groupμFisher's exact test used for categorical variables, Wilcoxon rank sum test for continuous variables. Disclosures:No relevant conflicts of interest to declare.